#1 - High chlorine is hard on swimwear, but usually not people. A facility I serviced once accidentally maintained a kiddie pool -- filled with infants daily -- at 50+ ppm for 3 days and ZERO complaints! But for more details, read the Best Guess page.

#2 - Sand usually fails only by not being there, which happens when the pump is too big for the filter, and sand gets blown out during backwash.

#3 - If your sand is there, your filter is probably working. If you added DE, and it didn't blow back into the pool, your filter is working.

#4 - Iron can be green -- but ONLY if you added in a soluble form. This typically only happens when filling from a well OR from old, old water lines made of cast or ductile iron. Rain water, even in hurricanes, is iron free.